I can't carry all those things in the car. Could you give me a hand?
There're too many things in the car to get by myself. Do you mind helping me?
この場合、次のような言い方ができますよ。
ーI can't carry all those things in the car. Could you give me a hand?
「車の中のものを全部運べないから、手伝ってくれませんか?」
ーThere're too many things in the car to get by myself. Do you mind helping me?
「車の中に荷物がいっぱいありすぎて、自分だけでは運べないので、手伝ってくれませんか?」
ご参考まで!